There’s more than one way to cook a quasicrystal. For the first time, a new kind of this weird, rule-breaking solid has been found in nature without an identical compound having first been made in the lab.
Paul Steinhardt at Princeton University has doggedly hunted for quasicrystals since he predicted their existence in the early 1980s. Before then, we only knew of two types of solids: crystals, in which every atom is arranged neatly in a repeating lattice, and amorphous solids, which have no such order. Quasicrystals are almost crystals, but they break the rules: their neat patterns never exactly repeat.
The first synthetic quasicrystal was grown in the lab in 1982, and there are now more than 100 types of lab-grown ones. But this is only the third type found in nature – all three from the Khatyrka meteorite from north-eastern Russia since 2009. The approximate composition of the first two had been created in a lab beforehand.
Finding a fresh example in nature allows us to continue writing a recipe for creating new quasicrystals from scratch, says Steinhardt. For one thing, all three seem to require metallic aluminium, which naturally bonds to oxygen except in this meteorite.
The new quasicrystal has a similar molecular structure to the first one, but slightly different chemistry: both are made of aluminium, copper and iron, but in different proportions. Steinhardt and his team had collected samples of the Khatyrka meteorite in 2011, and found the new material in a chip less than half a millimetre across.
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